1. Field of the Invention
The present invention relates to a compressor used for a vehicle air-conditioning system etc.
2. Description of the Related Art
A refrigeration circuit used in a vehicle air-conditioning system includes a compressor for compressing a refrigerant gas. This compressor comes in various forms such as variable displacement types and fixed displacement types. More specifically, fixed displacement type compressors include not only single-headed piston type swash plate compressors, but also double-headed piston type swash plate compressors. Variable displacement type compressors also include not only single-headed piston type swash plate compressors, but also double-headed piston type swash plate compressors.
Among these compressors, for example a single-headed piston type swash plate compressor defines and forms inside its housing cylinder bores, a crank chamber, a suction chamber, and a discharge chamber. Each cylinder bore accommodates a single-headed piston so that it may reciprocate. Further, a drive shaft supported rotatably by the housing is driven by an engine or another external drive source. The swash plate is supported by the drive shaft to be able to synchronously rotate with the drive shaft. A pair of shoes is accommodated in a pair of shoe seats, provided at an engagement portion in the piston, to drive the piston and a shoe is provided at each of the front and rear of the swash plate.
If the swash plate is inclined at a certain angle with respect to the drive shaft, the compressor is a fixed displacement swash plate compressor. If the inclination angle of the swash plate is variable with respect to the drive shaft and the pressure in the crank chamber can be adjusted by a control valve to change the inclination angle and adjust the discharge capacity, it is a variable displacement swash plate compressor. On the other hand, if the piston is a single-headed piston having a head at only one of the front and rear of the swash plate, the compressor is a single-headed piston type swash plate compressor. If the piston is a double-headed piston having heads at both the front and rear of the swash plate, it is a double-headed piston type swash plate compressor.
In this single-headed piston type swash plate compressor, if the drive shaft is driven by an external drive source, the swash plate synchronously rotates, so the pistons reciprocate in the cylinder bores through the shoes. Due to this, each cylinder bore forms a compression chamber with the head of the piston, so when the piston is in the suction stroke, low pressure refrigerant gas is sucked into the compression chamber from the suction chamber connected to an evaporator of the refrigeration circuit. When the piston is in the compression stroke, high pressure refrigerant gas is discharged to the discharge chamber from the compression chamber. This discharge chamber is connected to a condenser of the refrigeration circuit. The refrigeration circuit is used as a vehicle air-conditioning system for air-conditioning a vehicle.
During this time, in the single-headed piston type swash plate compressor, the slidability of the sliding portions between the swash plate and the shoes and between other members is ensured by a mist of lubricating oil contained in the refrigerant gas. Further, it is also possible to form a sliding layer of a sprayed layer for improving the slidability at the sliding portions.
In the above compressors of the related art, however, under severe conditions where the members slide at a high speed with respect to each other or where they slide at the time of a high heat load, the slidability of the sliding portions still was insufficient.
An object of the present invention is to provide a compressor with sliding portions having a high slidability.
According to the present invention, there is provided a compressor performing a compression action and having a sliding portion where one member slides with respect to another member, wherein the sliding portion is formed with a sliding layer including polyetheretherketone.
Preferably, the sliding layer is comprised of a binder comprised of polyetheretherketone and a solid lubricant dispersed in the binder.
Preferably, the compressor is provided with a swash plate and shoes sliding with the swash plate and sliding with pistons and the sliding layer is formed at least at one sliding portion of said shoes and pistons.
Preferably, the compressor is a swash plate type compressor with the swash plate. The swash plate drives the piston by the shoes accommodated in the piston and thereby the piston performs the compression action. The shoes are formed with sliding portions between one shoe and the swash plate and between the other shoe and the piston and the sliding layer is formed on at least one sliding portion of said swash plate, said shoes and said pistons.
Preferably, a housing of the compressor internally defines and forms cylinder bores, a crank chamber, a suction chamber and a discharge chamber. A drive shaft is rotatably supported by the housing and is driven by an external drive source. Further, the swash plate is supported by the drive shaft to be rotated with the drive shaft and the piston is accommodated in each of the cylinder bores to be able reciprocate therein and to define a compression chamber therein. Further, the swash plate is provided with a pair of shoes accommodated in a pair of shoe seats in the piston at the front and rear of the swash plate and drives the piston through the shoes accommodated in the piston and thereby the piston sucks refrigerant from the suction chamber and discharges compressed refrigerant into the discharge chamber. Further, the shoes are formed with sliding portions between one shoes and the swash plate and between the other shoe and the piston, and the sliding layer is formed on at least one sliding portion of said swash plate, said shoes and said pistons.